1. Field of the Invention
The present invention generally relates to an optical circuit that transfers information of an incoming information-bearing signal from a first wavelength to a second wavelength.
2. Background Information
Optical communication systems provide significant communications capacity using a point-to-point architecture, whereby one transmitter is connected directly to a remote receiver through a single optical fiber. One widely accepted approach used to further expand such communications capacity is implemented using a Wavelength Division Multiplex (“WDM”) system. In a WDM system, sources with different wavelengths (colors) used to carry their own information are combined and transmitted through a single optical fiber. Therefore, a WDM system employing 16 different wavelengths channels can increase the capacity of the optical fiber by 16 fold.
As optical systems evolve and become optical networks with more complex topologies (e.g., ring, star, etc.), there is a need to find ways to manage different channels having different wavelengths. Wavelength converters are used in dynamic and standard WDM networks to optically transfer information from one wavelength carrier to another. Such wavelength converters add flexibility to the networks by routing and reconfiguring channels therein.
Some current wavelength converters, also known as optical transponders, process an incoming optical signal at a first wavelength by converting the optical signal to an electrical signal. The electrical signal is then regenerated back to the optical domain at a different wavelength (i.e., Optical-Electrical-Optical, or OEO). This process is expensive, complex and has limited applications since it is limited to operating at a specific data rate.
Other known wavelength converters implement an all-optical methodology which uses techniques such as Four-Wave Mixing (“FWM”), Cross-Phase Modulation, Cross-Gain Modulation (“XGM”), or the like. These techniques require complex circuitry and are inefficient, thus leading to high conversion loss. For example, known wavelength converters which use XGM generally require a semiconductor optical amplifier (“SOA”) acting as a mixer in addition to a laser used as an oscillator. Such systems tend to be complicated and costly.